Thermal Hazards Reaction and Adiabatic Calorimetry Testing

Engineer running a test on the Mettler Toledo RC1 reaction calorimeter

Thermal stability (or thermal hazards) testing collects reaction rate data and applys that data to assess whether a specified quantity of material can be used in a way such that runaway reactions are avoided. This is important when considering processing, long-term storage, or shipping of a material. A comprehensive lab uses many tools to understand and eliminate undesired reactions, accommodate process upset scenarios and design a client’s desired process chemistry.

Do you recognize the importance of these in your thermal stability testing?

• Safe Scale-up
• Reaction Rates
• Heat of Reaction
• Heat of Mixing
• Heat of Dissolution
• Adiabatic Temperature Rise
• Heat Capacity of Reaction Mass
• Heat Flow and Adiabatic Calorimetry
• Low-phi Factor (directly scalable) adiabatic calorimetry
• UN Transport Testing
• Practical Emergency
• Vent Sizing (PrEVent^TM)
• Software

ChemiSens CPA202

Reaction calorimetry testing and consulting services are designed to help you better understand your desired process chemistry. One of the keys to safely scaling up a chemical process is managing the energy or heat flux that the intended chemical reaction produces, especially when that chemical transformation is exothermic in nature. When considering process scale-up whether the heat is removed via a jacket, a condenser, or a side loop heat exchanger in the plant reactor, or partially allowed to heat up the mass, it is imperative to balance the cooling capacity at scale versus the projected heat flux rate and understand the total energy available due to the desired reaction should that cooling fail. The accepted technique for gathering this type of data in the industry is known as reaction calorimetry.

There have been many instruments developed over the years to accomplish this task and Fauske & Associates, LLC (FAI) maintains a variety of devices so that we can design the most appropriate experiment to gather the vital heat rate and adiabatic potential data needed for a safe scale up. Couple this with our vast experience in characterizing runaway reaction behavior using adiabatic and vent sizing calorimetry and we can deliver you a complete picture of a safe chemical process.

We currently utilize three Reaction Calorimeters of varying size and capability:

THT-μ RC - The reactor is simply a GC vial or a metal pressure (SS or HC) cell, volume ~1.5 ml. Modes of operation include isothermal with steps, titration with an integrated syringe pump, scan and hold (2˚C/min max) and heat capacity determination. FAI is also developing this device for measuring binary compatibilities.

Mettler-Toledo RC1 - The RC1 is a heat flow calorimeter. As such, the heat leaving or entering the reactor is characterized by UA (Tr-Tj), where U is the overall heat transfer coefficient, A is the area of heat transfer and Tr and Tj are the temperature of the reactor and jacket, respectively.

ChemiSens - The ChemiSens is a heat flux calorimeter that provides a true heat flow signal without requiring any calibration. The heat transfer surface is entirely through the bottom of the reactor making use of Peltier technology, and is independent of the heat transfer coefficient as defined above.

Testing in the Thermal Activity Monitor (TAM®)

Adiabatic calorimetry testing provides data for relief system design, safe scale-up of chemical processes, and changes to process recipes.  Safe process design requires knowledge of chemical reaction rates, character and energy release - all of which can be obtained from a low phi-factor adiabatic calorimeter such as the VSP2^TM (Vent Sizing Package 2) or ARSST^TM (Advanced Reactive System Screening Tool).To determine critical safety parameters to avoid undesired reactions, FAI performs heat flow and adiabatic calorimetry using VSP2^TM, ARSST^TM, Thermal Activity Monitor (TAM), Seteram C80, Accelerating Rate Calorimeter (ARC®), Differential Scanning Calorimeter (DSC), Thermal Gravimetric Analysis (TGA), AKTS Software used to determine:

• Onset Temperature
• Time to Maximum Rate (TMR)
• 24 Hour Adiabatic Decomposition Temperature (ADT24)
• Temperature to Avoid Thermal Runaway - Critical Temperature of a Vessel
• Self-Accelerating Decomposition Temperature (SADT)

Low-phi factor (directly scalable) adiabatic calorimetry using the VSP2^TM & ARSST^TM provides information to understand and accommodate process upset scenarios. These tests determine:

• Adiabatic Temperature Rise Rates
• Adiabatic Pressure Rise Rates
• Pressure-Temperature Profile
• Design Vessel Relief Systems

If you enjoyed learning about adiabatic calorimetry, check out our case study on low thermal inertia adiabatic calorimetry.  In this case study, FAI performs tests to determine what is the self accelerating decomposition temperature of a 50 kg package of azodicarbonamide. Download the case study now to to learn more about AKTS software, self accelerating decomposition temperature, the United States SADT test, and much more.